Mild to Moderate Medial Collateral Ligament (Mcl) Injuries of the Knee: Sonographic Findings and Sonographic Valgus Stress Test

Abstract

The purposes of this study are to describe the sonographic findings of the injured medial collateral ligament (MCL) of the knee, to perform a sonographic valgus stress test, and to correlate these findings in order to advance the proper treatment for these patients. We examined 23 patients with clinical diagnosis of MCL injury. We evaluated proximal and distal MCL thickness, free fluid, and avulsion fractures. In addition, we performed a sonographic valgus stress test in the stress and rest positions. We also examined the knee joint on the same side in 18 sex-and age-matched patients with no history of knee injury as a control. The average thickness of proximal MCL was 6.4 mm (range, 4.2-8.1 mm) in injured MCL and 4.3 mm (range, 3.2-6.2 mm) in normal MCL. The average thickness of distal MCL was 4.4 mm (range, 2.4-6.1 mm) in injured MCL and 3.1 mm (range, 2.1-4.1 mm) in normal MCL. The average joint space width of the injured knee at rest was 6.1 mm (range, 4.0-8.5 mm) and increased to 10.5 mm (range, 7.6-14.0 mm) after stress. The average joint space width of the normal knee at rest was 6.7 mm (range, 5.0-7.7 mm) and increased to 9.6 mm (range, 7.7-10.4 mm) after stress. In conclusion, the combination of the sonographic findings in MCL injury and the real-time sonography valgus stress test can support the clinical diagnosis and pinpoint the exact location of isolated MCL injury, thus advancing the proper treatment of the patient.

The measurement of medial knee gap width using ultrasound

“…Some differences between the results from the current study and those in the literature may be due to differences in loading. LaPrade et al [24] reported that gap width was measured during the application of a 10 Nm load, as in our study, whereas Kleinbaum and Blankstein [33] and Whelan et al [25] either did not control load or did not report it …”

“…This has clinical implications. For example, there is evidence that MCL-deficient knees show significantly greater values of absolute gap width compared with intact knees [24, 25, 33], and medial gap width may be a suitable method for assessing the efficacy of MCL repair [25]. Varus/valgus instability post-arthroplasty, which has been linked to patient satisfaction [11], and is often assessed clinically with radiographic examination, may also be possible to evaluate with ultrasound, though reverberation artifacts off of the metallic prosthesis [41] may make gap width measures more challenging in these cases.…”

“…To our knowledge, there is only one study that has used an US method for measuring medial gapping in the knee [33], and there is no comprehensive comparison between this and the gold standard. We hypothesized that an US method would be capable of measuring the increase in the medial gap of the knee with valgus loading.…”

Comparing Point-of-care-ultrasound (POCUS) to MRI for the Diagnosis of Medial Compartment Knee Injuries

“…Both the layers of the MCL are sonographically hyperechoic structures and are separated by a hypoechoic band, consisting of areolar tissue. This gives the MCL a trilaminar structure with the hyperechoic outer parts and a hypo-echoic inner part [ 7 8 9 18 19 ]. However, when injured, the trilaminar appearance is often lost and the MCL becomes hypoechoic and heterogenous, thought to be due to edema.…”

“…One of the most common mechanisms for knee injury is direct trauma, which is commonly seen in athletic injuries [ 3 ]. When injury occurs, the superficial MCL is the most commonly damaged ligament of the knee, usually induced by valgus stress, and can occasionally be accompanied by a tear in the medial meniscus [ 4 9 ]. While clinical examination is essential in diagnosing tears of the medial compartment of the knee, imaging is often required to make a conclusive diagnosis [ 3 ].…”